/tags/release-0.1-rc2/hive/external/ql/src/java/org/apache/hadoop/hive/ql/lib/NodeProcessor.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hive.ql.lib;

import java.util.Stack;

import org.apache.hadoop.hive.ql.parse.SemanticException;

/**
 * Base class for processing operators which is no-op. The specific processors
 * can register their own context with the dispatcher.
 */
public interface NodeProcessor {

  /**
   * Generic process for all ops that don't have specific implementations.
   * 
   * @param nd
   *          operator to process
   * @param procCtx
   *          operator processor context
   * @param nodeOutputs
   *          A variable argument list of outputs from other nodes in the walk
   * @return Object to be returned by the process call
   * @throws SemanticException
   */
  Object process(Node nd, Stack<Node> stack, NodeProcessorCtx procCtx,
      Object... nodeOutputs) throws SemanticException;
}